Transpiration

• the constant flow of water from roots to leaves is called the transpiration system
• transpiration is the loss of water vapour mainly from the leaves
• transpiration and transpiration system are different because transpiration is the loss of water vapour and transpiration is the whole network of water moving through the plant
• appearance of xylem - long narrow tube and lignin spirals
• suggest how celery left in dye could be used to measure the rate of the flow of water up a stem- measuring how far up the dye has reached in a set period of time. the further the ink has moved, the faster the water
• water moves through a plant via transpiration stream. water diffuses into the root hair cells, then into the xylem vessels where its transported to the leaves. water is then lost from the plant through the stomata by transpiration
• how stomata are opened and closed - water vapour evaporates from air spaces out of the stomata, stomata are opened and closed by guard cells, guard cells take up water by osmosis and swell - opening the stomata. guard cells lose water becoming floppy- closing the stomata and reducing water loss